Is there a difference in the amount of airborne bacteria between carpeted and uncarpeted rooms? in an experiment, 7 rooms were carpeted and 7 were left uncarpeted. the rooms are similar in size and function. after a suitable period of time, the concentration of bacteria in the air was measured (in units of bacteria per cubic foot) in all of these rooms. assume the populations are normally distributed. the data and summaries are provided:

x s

carpeted rooms: 184 22.0

uncarpeted rooms: 175 16.9

15. a 95% confidence interval for the difference in mean bacterial concentration in the air of carpeted rooms versus uncarpeted rooms is (use 11 degrees of freedom).

a. –7.47 to 31.47.

b. –18.89 to 42.89.

c. –16.66 to 34.66.

d. –14.02 to 32.01.

16. the researcher wants to investigate whether carpet makes a difference (either increases or decreases) in the mean bacterial concentration in air. the numerical value of the two-sample t statistic for this test is

a. 0.414

b. 3.818

c. 1.312

d. 0.858.

17. the p-value for the test described above is approximately 0.42, what can be concluded from the hypothesis test.

a. there is no evidence of a difference between the average amount of bacteria in the carpeted and uncarpeted rooms.

b. fail to reject the null hypothesis at a significance level of 0.05.

c. the null hypothesis is true.

d. both a and b are true.

can you provide the steps